Portable cushions are frequently used to increase the comfort of chairs, car seats, benches, and the like. Such prior art devices have generally attempted to either improve the convenience and portability of such cushions, or to improve the supporting shape of the cushions. For example, U.S. Pat. No. 4,190,918 to Harvell on Mar. 4, 1980, teaches a cushion device with improved portability in that two cushions are flexibly attached and carryable with a handle arrangement. Such a device is easier to carry than two separate cushions. Another such device is illustrated in U.S. Pat. No. De. 258,482 to Strock on Mar. 10, 1981. Both of these devices, however, require carrying by hand, which can be inconvenient if both hands are needed elsewhere. Moreover, people with back problems will find supporting such a device with one arm uncomfortable and potentially harmful to the back, especially if side pockets of such a device are heavily loaded.
Another device, disclosed in U.S. Pat. No. De. 279,642 to Ross on Jul. 16, 1985, is typical of back cushioning devices with contoured supporting shape for the lumbar region of a person's back. U.S. Pat. No. De. 268,976, issued on May 17, 1983, also to Ross, illustrates another such device. Such devices, however, are most effective when used in combination with a supporting seat cushion. Such a device is inconvenient to carry from place to place with a separate seat cushion device, and therefore such devices are limited in their usefulness as portable items with two separate parts.
Accu-Back, Inc., of California, makes available an orthopedic foam wedge which serves as a supporting seat cushion. With the thickest portion of the wedge behind the knees, the thighs are elevated, thereby attempting a more natural, neutral position of the pelvis. However, such a wedge has limited effectiveness when used for extended periods of time, even when used with a supporting back cushion as suggested by the manufacturer. When elevating the thighs, such a wedge transfers body weight onto the coccyx and ischia, which often causes poor circulation and pressure pain in that area when sitting for extended periods. Moreover, the right angle corner design of the typical wedge device increase pressure against the back of the knees which may cause a reduction in blood circulation and cramping in the lower legs and feet. The manufacturer notes that such a wedge device may be used with the thickest portion under the buttocks, thereby relieving some pressure from the ishia and coccyx. Such a configuration is often recommended for people having injuries to the coccyx, or tenderness after surgery or childbirth, and the like. However, in such a wedge configuration, the pelvis may be forced out of a neutral position since the thighs are no longer elevated. Further, much of the body weight is shifted onto the back of the thighs and the back of the knees, often causing poor circulation to the lower legs and pain when sitting for extended periods of time.
Another seat support device, marketed under the tradename Bottoms-Up.TM., is made available by Roloke Co. of Culver City, Calif., and has a multiple-contoured surface. Roloke Co. claims that such a device achieves neutral balanced pelvic-spinal alignment. However, such a device has been found to be less effective if not used with a properly positioned lumbar-supporting back cushion since it is difficult for one to maintain correct posture over extended period of time without supporting the entire surface of the back of the pelvis. Such a seat support device only provides support to the lower back area up to the base of the pelvis. Although Roloke Co. strongly suggests using a back support device in combination with the Bottoms-Up.TM. device, handling separate back and seat supports is cumbersome. Further, since the Bottoms-Up.TM. device is a rigid appliance, prolonged use the device can become uncomfortable, and transporting and storing the device is often difficult and inconvenient.
Clearly there is a need for a support device designed to significantly reduce pressure to the ishia and coccyx regions while elevating the thighs to facilitate moving the pelvis into a more neutral and orthopedically correct position. Such a needed device would also eliminate pressure to the back of the knees to allow proper blood circulation throughout the legs and feet while sitting over an extended period of time. Further, such a needed device would redistribute body weight more evenly over the entire seating surface without requiring a rigid seating surface that is cumbersome and inconvenient to transport. Such a needed device would further include a lumbar support means to support and increase comfort across the entire back of the pelvis and effectively neutralize the pelvic-spinal alignment for extended sitting periods. Still further, such a needed device would be extremely light weight and convenient to use and carry, would be fully adjustable so as to accommodate a variety of sizes of users and seat depths, and would be relatively inexpensive to manufacture. The present invention fulfills these needs and provides further related advantages.